This invention relates to cosmetic composition products and to the formulation of such products. Some of the products which can be prepared by skilled cosmetic chemical formulators based upon the anhydrous cosmetic lotion of this invention include suntan lotions, facial lotions, hand lotions, body lotions, topical steroid treatment lotions and creams, preshave lotions, rub down lotions, and insect repellants, just to name a few.
Topical products such as those mentioned in the preceding paragraph which are now commercially available, are generally comprised of either oil in water emulsions, water in oil emulsions, all oil soluble products, or all water soluble products. Of course, the oil and water products and likewise, the water and oil products, are emulsions wherein two immiscible components are intimately admixed and emulsified. While there are certain advantages to be obtained from use of either oil in water emulsions, or water in oil emulsions as the base for topical lotions, there are also significant draw backs from the use of such systems. Some of the drawbacks are that the water phase is easily washed off, and if the active ingredient is water soluble, the active ingredient in the topical lotion is washed off; and, therefore the effective treating time of the product is significantly reduced; also, such products often have a slow "rub-in" time. Further, products which contain water as part of the topical lotion base will support the growth of micro-organisms resulting in spoiled or unacceptable products. Therefore, these necessitate the addition of preservatives such as antimicrobial agents. Of course, the addition of such preservatives not only significantly increases the expense of the product, but also the chemical exposure risk to the consumer. Moreover, products which are either oil in water emulsions or water in oil emulsions are in many instances not cosmetically attractive to consumer users because the user recognizes the short life of the product on the skin. Often a negative reaction caused by the lack of desirable skin feel makes the consumer conclude that the product is ineffective, or the product may lack aesthetics.
Additionally, emulsion products based upon oils and water must contain stabilizing emulsifying agents in order to prevent separation into distinct, unsightly layers. Moreover, the microbial attack susceptibility of the water phase makes the propensity for separation even greater in that microbial growth may decrease the emulsion stability.
All oil topical lotions likewise have significant deficiencies in that, in many instances, the consumer does not regard such products as "cosmetically elegant". "Cosmetically elegant", is a term used in the cosmetic formulation art to describe a product which is attractive appearing, has good skin feel, is non-greasy, not tacky, spreadable, and soft. All of these terms generally relate to the consumer user's rating of the product in terms of its attractiveness and skin feel. All oil products are often regarded as not cosmetically elegant in that they tend to have an excessively greasy feel, and often may stain clothing or other items coming into contact with them.
Likewise, water soluble products have certain deficiencies. The primary deficiency of such products is short treating life on the skin since they are easily washed off. Additionally, the products containing large amounts of water, as heretofore explained, are highly susceptible to microbial attack and complications resulting therefrom. Additionally, many water based products are often described by the consumer user as lacking cosmetic elegance. They lack good skin feel, giving an overall impression of wetness, and lack of substantivity, with the consumer paying for a product often containing 60% water, which in itself has no therapeutic value for the skin.
It therefore can be seen that topical lotion products as prepared by cosmetic chemical formulators, generally involve a balancing, and trade off, of the good and bad points of the four basic types of topical lotions: namely oil in water emulsions; water in oil emulsions; oleaginous lotions; or, all water soluble lotions. While each has certain advantages, each also has significant disadvantages. It is for the reason of this balancing and trade off of properties that most formulators for the most part have abandoned all oil and all water soluble products and gone to topical lotion preparations which are either oil in water emulsions or water in oil emulsions.
The fundamental object in preparing such products is to prepare something which is a good emollient, physiologically compatible, a good skin moisturizer, a product which is cosmetically elegant, and a product which has the added benefit of the base topical composition providing for increased and/or prolonged activity of any added active ingredient, such as sun screens, insect repellants, humectants, moisturizers, medicinals or the like.
One fundamentally important criteria by which many such topical lotions must be measured is their ability to act as efficient skin moisturizers.
Skin moisturizing ability is of extreme importance for topical lotions in that consumers regard scaly, dry skin as unsightly and undesirable. Thus, products which are topical lotions and have the added benefit of enhancing skin moisture retention capabilities, have a significant added benefit above and beyond the utility of their active ingredient, whether a sunscreen, an insect repellant, or the like.
Much has been written on the causitive factors for dry and scaly skin. As those skilled in cosmetic formulation theorize, when one speaks of dry and scaly skin, one is speaking of the loss of water from the stratum corneum, which is the outermost dead layer of skin. It is believed that whenever moisture is removed from the stratum corneum, it loses its soft suppleness and becomes dry and scaly. While much has been written about the stratum corneum and its natural moisturizing factor, referred to as "NMF", intensive investigations into the causes of dry skin have largely left only theories to date.
Some cosmetic scientists believe that dryness is due to a loss of the water binding fatty materials from the stratum corneum layer, while others state that dry skin really does not lack water. Most, however, seem to agree that four basic stages are involved in the development of dry skin. In the first stage, there is removal, during cleansing, of the sebum that protects water binding materials in the stratum corneum against being leached out. In the second stage, there is in fact leaching out of the water binding components of the stratum corneum. In the third stage after water evaporation and dehydration, there is a loss of flexibility of the stratum corneum cells. Finally, in the fourth stage, cracking of the stratum corneum occurs, allowing penetration of micro-organisms and irritant materials into the epidermis. In extreme cases, infections, irritations and rashes result.
To date, the state of the art with regard to topical lotions involves reduction of water loss from the stratum corneum by two basic methods. In the first approach to the problem there is a deposit of an occlusive barrier layer to prevent water evaporation from the stratum corneum, the theory being that the deposit of, for example, petrolatum over the stratum corneum will act as a barrier to prevent water escape outwardly therefrom. However, consumer users of such products often do not react favorably to such barrier creation in that they describe it as not cosmetically elegant, greasy, and often sticky. The second approach is to add hygroscopic substances to the stratum corneum in the hope that such substances will draw moisture which will penetrate into the stratum corneum, replacing lost moisture. It is upon this theory that such compounds as sodium lactate and sodium pyrolidone carboxylic acid (PCA) are often added to topical lotions. Both sodium lactate and sodium pyrolidone carboxylic acid have been reported as naturally occurring in the stratum corneum. The use of such hygroscopic substances, however, has not proven to be effective in providing a beneficial effect.
In summary, an effective topical composition must be an efficient moisturizer and substantive, whatever else it is. An efficient moisturizer may be defined as a substance that overcomes the signs and symptoms of dry skin. This is interpreted by the consumer user as providing a cosmetically elegant skin feel. As can be seen, there are numerous deficiencies with most topical compositions, whether oil in water emulsions, water in oil emulsions, all oil soluble phase or all water soluble phase. If the formulation contains high amounts of water there is a significant danger of bacterial growth and if the product is an emulsion, a danger of emulsion instability. Products containing large amounts of water easily wash off, have a short useful life, a short shelf life, and the water itself from the product contributes nothing to the efficacy.
Moreover, many of the topical lotion products now on the market merely provide a physical barrier which is impervious to moisture, hoping that the skin will retain the moisture it has, rather than providing a physiologically active agent for effective treatment of dry skin that is enduring. Moreover, in many instances in order to provide an enhanced degree of effective moisturization, there must be a corresponding sacrifice of cosmetic elegance.